JP2022533015A - Terminal busbar for safety improvement, battery module and battery pack including it - Google Patents

Abstract

To provide a terminal bus bar as a component capable of improving the safety of a battery module, a battery module including the same, and a battery pack. A terminal bus bar according to the present invention includes a generally plate-like coupling portion having a thickness smaller than its length and width, and a terminal portion vertically bent at one end of the coupling portion. The coupling portion is formed from a first metal layer laminated in order along the extension direction of the terminal portion/a material layer which is normally conductive but functions as a resistance when the temperature rises/a second metal layer. The material layer includes a gas generating material that is decomposed above a predetermined temperature to generate gas to increase resistance. The first metal layer is integral with the terminal portion, and the second metal layer provides a connection surface with an electrode lead of a battery cell.

Description

The present invention relates to a battery module, and more particularly to a battery module capable of interrupting the flow of electric current when the temperature rises. The present invention also relates to a terminal bus bar that can be used in such a battery module, and a battery pack that includes such a battery module.

This application claims priority based on Korean Patent Application No. 10-2019-0068725 filed on June 11, 2019, and all the contents disclosed in the specification and drawings of the relevant application are incorporated into this application. ..

Currently, commercialized secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, lithium secondary batteries, etc. Among them, lithium secondary batteries have a memory effect compared to nickel-based secondary batteries. It is in the limelight because it has the advantages of being free to charge and discharge, having a very low self-discharge rate, and having a high energy density.

Such a lithium secondary battery mainly uses a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery has a structure in which a positive electrode plate in which a positive electrode active material is coated on a positive electrode current collector and a negative electrode plate in which a negative electrode active material is coated on a negative electrode current collector are arranged with a separation film interposed therebetween. It includes an electrode assembly in which unit cells are assembled, and an exterior material for sealing and storing the electrode assembly together with an electrolytic solution, that is, a battery case. Depending on the shape of the exterior material, the lithium secondary battery can be divided into a can-type secondary battery in which the electrode assembly is housed in a metal can and a pouch-type secondary battery in which the electrode assembly is housed in an aluminum laminated sheet pouch. Divided.

Recently, secondary batteries are widely used not only in small devices such as portable electronic devices but also in medium and large devices such as automobiles and power storage devices (ESS). When used in such medium and large equipment, a plurality of secondary batteries are electrically connected in order to increase the capacity and output. In particular, pouch-type secondary batteries are often used for such medium- and large-sized devices because of their advantages such as easy stacking and light weight. The pouch-type secondary battery has a structure in which an electrode assembly to which electrode leads are connected is housed in a pouch case together with an electrolytic solution and sealed. Some of the electrode leads are exposed to the outside of the pouch case, and the exposed electrode leads either electrically connect to the device in which the secondary battery is mounted, or electrically connect between the secondary batteries. Used for.

FIG. 1 shows a part of a battery module manufactured by connecting a pouch type battery cell. For example, it shows a state in which two pouch-type battery cells are connected in series.

As shown in FIG. 1, the pouch-type battery cells 10, 10'include two electrode leads 40, 40' that are drawn out of the pouch case 30. The electrode leads 40 and 40'are divided into a positive electrode (+) lead and a negative electrode (−) lead according to the electrical polarity, and are electrically connected to the electrode assembly 20 sealed in the pouch case 30. That is, the positive electrode lead is electrically connected to the positive electrode plate of the electrode assembly 20, and the negative electrode lead is electrically connected to the negative electrode plate of the electrode assembly 20.

There are various methods for connecting the battery cells 10 and 10'in the battery module 1, but in FIG. 1, after bending the electrode leads 40 and 40', they are placed on the bus bar 50 and welded by laser welding. The method of connecting the electrode lead 40 of the battery cell 10 and the electrode lead 40'of another battery cell 10'adjacent to the battery cell 10 is shown.

On the other hand, a lithium secondary battery has a risk of explosion when it is overheated. In particular, as it is applied to electric vehicles including electric vehicles (Electric Battery, EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (Plug-in Hybrid Electric Vehicle, PHEV), etc. In a battery module or battery pack that is used by connecting a high-capacity secondary battery battery cell, a very large accident may occur at the time of explosion, and ensuring safety is one of the main issues.

A typical cause for the temperature of a lithium secondary battery to rise sharply is the flow of a short-circuit current. The short-circuit current is mainly generated when a short-circuit occurs in an electronic device connected to the secondary battery, and when a short-circuit occurs in the lithium secondary battery, a rapid electrochemical reaction occurs at the positive electrode and the negative electrode, and heat is generated. Will come to do. The heat generated in this way causes the temperature of the battery cell to rise at a high speed, eventually causing ignition. In particular, in the case of a battery module or battery pack containing multiple battery cells, the heat generated in any one battery cell is propagated to the surrounding battery cells and affects the other battery cells. , This can lead to even greater danger.

Therefore, a PTC element, a fuse, or the like has been proposed as a means for blocking the current and preventing an explosion when the temperature inside the secondary battery rises. However, these have a problem that another mounting space is required in the battery module or the battery pack.

It is very important to ensure safety in that an explosion of a battery module or battery pack not only causes damage to the electronic equipment or automobile in which it is used, but also threatens the safety of the user and can lead to a fire. Is. When a secondary battery is overheated, the risk of explosion and / or ignition increases, and rapid combustion or explosion due to overheating can cause personal and property damage. Therefore, a means for ensuring sufficient safety in use of the secondary battery is required.

An object of the present invention is to provide a component capable of improving the safety of a battery module by interrupting an electric current when the temperature rises.

Another object of the present invention is to provide a battery module and a battery pack having improved safety by adopting such a component.

Other objects and advantages of the present invention will be understood by the description below and will be more apparent by the examples of the present invention. In addition, the objects and advantages of the present invention can be realized by means and combinations thereof shown in the claims.

In the present invention, a new terminal bus bar is proposed as a component that can improve the safety of the battery module.

The terminal bus bar according to the present invention includes a substantially plate-shaped joint portion having a thickness smaller than the length and width, and a terminal portion bent in a direction perpendicular to one end of the joint portion. The joint portion is formed from a first metal layer / a second metal layer that is normally laminated in order along the extension direction of the terminal portion / is always conductive, but functions as a resistance when the temperature rises. Therefore, the substance layer contains a gas generating material that increases resistance by being decomposed at a predetermined temperature or higher to generate gas. The first metal layer is integrated with the terminal portion, and the second metal layer provides a connecting surface with the electrode leads of the battery cell.

In such a terminal bus bar, a through hole through which the electrode lead penetrates may be formed at the joint portion.

The material layer may contain the gas generating material, a conductive material and an adhesive.

The gas generating material can be melamine cyanurate.

The conductive substances are connected and fixed to each other by the adhesive, and when the gas is generated, the connection of the conductive substances can be released and the resistance can be increased.

A method of manufacturing such a terminal busbar may include the following steps. First, a metal member having a first metal layer integrated with a terminal portion and an L-shaped cross section is prepared. The substance layer is formed on the first metal layer. Then, the second metal layer is laminated on the material layer.

When the substance layer is formed to contain the gas generating material, the conductive substance, and the adhesive, the step of laminating the second metal layer on the substance layer and then pressing the substance layer may be further included.

The battery module according to the present invention includes such a terminal bus bar.

This battery module is a battery module including two or more battery cells, wherein the battery cell is a pouch-type secondary battery in which electrode leads of opposite polarities are exposed to the outside of the pouch case. Further includes a terminal bus bar connected to the electrode leads of one or more of the battery cells.

In such a battery module, a current flow path from the outside of the battery module to the battery module is provided in the order of the terminal portion, the first metal layer, the material layer, the second metal layer, and the electrode lead. obtain.

The present invention also provides a battery pack containing two or more such battery modules. This battery pack is an interbus bar that connects the terminal portion of one of the terminal bus bars of the battery modules and the terminal portion of the other terminal bus bar of the battery modules in order to connect the battery modules to each other. Including further. The battery pack may further include a pack case for packaging the battery module.

The present invention provides an automobile, which comprises at least one battery pack according to the present invention.

According to the present invention, the battery module is configured by changing the terminal bus bar while leaving the battery cell as it is. The terminal bus bar can cut off the current flow through the terminal bus bar by increasing the resistance when the temperature rises. Therefore, when the battery module according to the present invention is used, the current flow can be cut off in the case of overheating, and safety in an abnormal situation can be ensured.

As a configuration of increasing the resistance of the bus bar, a substance layer containing a gas generating material is included in the bus bar so that the flow of electric current is cut off when the temperature at which the gas generating material is decomposed is reached. This makes it possible to block the flow of current even when the secondary battery protection circuit does not operate so that no more current flows, for example, to prevent charging, and the battery module. Can increase the safety of the. As described above, the battery module of the present invention has a dual battery module with an overcharge prevention function of the secondary battery protection circuit in order to realize a means for automatically shutting off the current flow when the temperature rises by improving the bus bar. It also has the effect of ensuring the safety of the battery.

According to the present invention, it is possible to provide a battery module using a terminal bus bar that can ensure safety when connecting battery cells to each other to form an electrical connection path. When an event such as a situation where an abnormal temperature is reached occurs, the gas generating material contained in the material layer in the terminal bus bar is decomposed and the resistance increases. As a result, the battery cell is disconnected from the electric connection and the current flow is cut off, so that the safety of the battery module can be ensured.

In particular, by including a material layer containing a gas generating material that increases resistance by decomposing at a predetermined temperature or higher to generate gas between the first metal layer and the second metal layer in the terminal bus bar. , The resistance between the second metal layer, which is the portion where the terminal bus bar and the electrode leads are connected around this material layer, and the first metal layer, which is the terminal bus bar portion where the electrode leads are not connected, increases. Therefore, it is configured so that no current flows. Such a terminal bus bar is also used to connect adjacent battery modules in particular. When the terminal bus bar that connects the battery cells between the adjacent battery modules is configured in this way, the current does not flow through the terminal bus bar when the temperature rises, and the safety is improved.

According to the present invention, safety is ensured by improving the terminal bus bar of the battery module. Only the terminal bus bar proposed in the present invention is used instead of the existing terminal bus bar, and the existing battery module manufacturing process can be used as it is. Therefore, the safety of the battery module is ensured relatively without any change in the process. It has the advantage of being able to do it. Since the battery cell itself uses the existing manufacturing process as it is, there is no need to change the process or adjust the mass production process.

As described above, according to the present invention, the current flow is ensured under normal conditions, and the current flow is cut off when the temperature rises above a predetermined temperature due to an abnormal condition, while exhibiting battery module performance similar to the existing one. This can improve the safety of the battery module. Therefore, it is possible to improve the safety of the battery module, the battery pack including the battery module, and the vehicle including such a battery pack.

The following drawings, which are attached to the present specification, exemplify a desirable embodiment of the present invention, and serve to further understand the technical idea of the present invention as well as a detailed description of the present invention. It should not be construed as being limited to the matters described in the drawings.

A conventional battery module is shown schematically. It is a terminal bus bar according to an embodiment of the present invention. It is a terminal bus bar according to another embodiment of the present invention. It is a figure which showed schematicly the battery module including the terminal bus bar by another Example of this invention. It is a front view of the terminal bus bar part included in the battery module of FIG. It is sectional drawing of the terminal bus bar part included in the battery module of FIG. It is a front view of the bus bar part included in the battery module of FIG. It is a photograph of an ICB assembly manufactured experimentally. It is a figure for demonstrating the battery pack by still another Example of this invention. It is a figure for demonstrating the automobile by still another Example of this invention. It is a graph which showed the resistance and temperature by time of the battery module used for an experiment. It is the result of the external short circuit test of the battery module used in the experiment. It is the result of the external short circuit test of the battery module used in the experiment. It is the result of the external short circuit test of the battery module used in the experiment. It is the result of the external short circuit test of the battery module used in the experiment.

Hereinafter, desirable embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the present specification and the scope of the patent claim should not be construed in a general or lexical sense, and the inventor himself describes the invention in the best possible way. Therefore, it must be interpreted in the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that the concept of terms can be properly defined.

Therefore, the embodiments described herein and the configurations shown in the drawings are merely one of the most desirable embodiments of the present invention and do not represent all of the technical ideas of the present invention. It must be understood that at the time of filing, there may be a variety of equivalents and variants that can replace them.

In the embodiments described below, the secondary battery refers to a lithium secondary battery. Here, the lithium secondary battery is a general term for a secondary battery in which lithium ions act as working ions to induce an electrochemical reaction between a positive electrode plate and a negative electrode plate during charging and discharging.

On the other hand, the name of the secondary battery depends on the type of electrolyte and separation film used in the lithium secondary battery, the type of battery case used to package the secondary battery, and the internal or external structure of the lithium secondary battery. Any secondary battery in which lithium ions are used as working ions even if is changed is interpreted as being included in the category of the lithium secondary battery.

The present invention is also applicable to other secondary batteries other than the lithium secondary battery. Therefore, even if the working ion is not lithium ion, any secondary battery to which the technical idea of the present invention can be applied is interpreted as being included in the category of the present invention regardless of its type.

Hereinafter, examples of the terminal bus bar of the present invention will be described with reference to FIGS. 2 and 3.

FIG. 2 is a terminal bus bar according to an embodiment of the present invention. FIG. 3 is a terminal bus bar according to another embodiment of the present invention.

First, referring to FIG. 2, the terminal bus bar 150 includes a coupling portion 160 and a terminal portion 170. The terminal portion 170 is a portion bent in the direction perpendicular to one end of the joint portion 160.

The joint portion 160 is a substantially plate-shaped member having a thickness T thinner than a length L and a width W. The coupling portion 160 is a first metal layer 162 / always conductive, which is laminated in this order from the bottom to the top along the extension direction of the terminal portion 170, but when the temperature rises, the material layer 164 / th is capable of functioning as a resistance. It consists of two metal layers 166. The first metal layer 162, the material layer 164, and the second metal layer 166 are laminated along the thickness T direction. The thickness of the terminal portion 170 may be the same as the thickness T of the coupling portion 160. The first metal layer 162 is integrated with the terminal portion 170, and the second metal layer 166 provides a connecting surface with the electrode leads of the battery cell. The terminal 170 can be used to connect external inputs or battery modules to each other. Normally, a component that is connected to an electrode lead to form an electrical wiring is called a bus bar, so a component that includes a coupling portion 160 and a terminal portion 170 may be called a bus bar, but unlike other bus bars, other than the coupling portion 160. In the present invention, the term "terminal bus bar" is used because the terminal portion 170 is further included in the terminal portion 170.

The first metal layer 162 and the second metal layer 166 may contain a metal having good electrical conductivity. For example, it may contain at least one of aluminum, copper, nickel and SUS. As the first metal layer 162 and the second metal layer 166, various materials used as existing busbar materials can be used. The first metal layer 162 and the second metal layer 166 may be of the same type or different types from each other.

The substance layer 164 sandwiched between the first metal layer 162 and the second metal layer 166 contains a gas generating material that increases resistance by being decomposed at a predetermined temperature or higher to generate gas. Desirably, the material layer 164 contains such a gas generating material and a conductive material and an adhesive. The conductive substances are connected and fixed to each other by the adhesive, and when gas is generated in the gas generating material, the conductive substances can be disconnected and the resistance can be increased. The gas generating material can be a volume expansion resin.

The gas generating material is preferably melamine cyanurate, which is a kind of volume expansion resin. Melamine cyanurate is a substance used as a nitrogen-phosphorus flame-retardant component in which nitrogen and phosphorus are combined, and can be obtained from various manufacturers in a raw material state having an average particle size of several tens of μm.

Melamine cyanurate, commonly used in flame-retardant applications, undergoes endothermic decomposition at temperatures above about 300 ° C. Melamine cyanurate is decomposed into melamine and cyanuric acid. Vaporized melamine releases inactive nitrogen gas. By adjusting the molecular weight of melamine cyanurate, the decomposition temperature can be adjusted. The structural formula of melamine cyanurate is as follows.
[Structural formula]

The conductive substance is not particularly limited as long as it has conductivity. For example, graphite such as natural graphite and artificial graphite; carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon dioxide, aluminum, silver and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives can be used.

The adhesive is a component that helps bond the gas generating material to the conductive substance or the like and bond to the first metal layer 162 and the second metal layer 166. Examples of such adhesives include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer ( EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers and the like.

When the temperature rises above a predetermined temperature due to an abnormal situation, for example, when the temperature rises above 300 ° C., melamine cyanurate is decomposed in the substance layer 164 interposed between the first metal layer 162 and the second metal layer 166. ₂ Gas is generated. As a result, the material layer 164 has increased resistance and functions as a resistance layer.

The method of manufacturing such a terminal bus bar 150 may include the following steps. First, a metal member M in which the first metal layer 162 is integrated with the terminal portion 170 and has an L-shaped cross section is prepared. In order to make the overall thickness T, the metal member M may be provided with the first metal layer 162 thinner than the terminal portion 170. Such a metal member M can be made by processing a metal plate material. After that, the material layer 164 is formed on the first metal layer 162. Then, the second metal layer 166 is laminated on the material layer 164. The thickness of the material layer 164 and the second metal layer 166 can be set so as to satisfy the thickness T as a whole when these are laminated on the first metal layer 162.

When the substance layer 164 is formed to contain the gas generating material, the conductive substance, and the adhesive, the step of laminating the second metal layer 166 on the substance layer 164 and then pressing the substance layer 164 may be further included.

The substance layer 164 can be formed by applying a paste or slurry, which is a mixture of the gas generating material, a conductive substance, and an adhesive, onto the first metal layer 162. When the second metal layer 166 is arranged on the second metal layer 166 and pressed downward from above, a terminal bus bar 150 in which the material layer 164 is sandwiched between the two metal layers 162 and 166 is obtained. If necessary, further heat treatment may be performed.

The thickness T of the joint 160 may be the same as the thickness of the existing busbar. The first metal layer 162 and the second metal layer 166 can also be made of the same material as the existing bus bar. The constant electrical conductivity of the material layer 164 can be made similar to the electrical conductivity of the existing busbar by making the conductive material in the material layer 164 the same as or higher than the existing busbar material. can.

Therefore, under normal circumstances, the conductivity of the material layer 164 in the terminal bus bar 150 can be maintained to exhibit battery module performance similar to that of using an existing bus bar. When the temperature rises above a predetermined temperature due to an abnormal situation, the resistance of the material layer 164 increases, so that the current flow can be cut off. As a result, when the temperature rises, the material layer 164 functions as a resistance to cut off the current, so that the safety of the battery module manufactured including the material layer 164 can be improved.

The terminal bus bar 150'shown in FIG. 3 is basically the same as the terminal bus bar 150 of FIG. The terminal bus bar 150'is further formed with a through port 168 through which the electrode lead penetrates at the coupling portion 160. The number of through holes 168 can vary depending on the number of electrode leads and the connecting method. A hole 172 is further formed in the terminal portion 170. Hole 172 is used to connect external inputs or battery modules to each other. The number of holes 172 may vary depending on the connection method.

As described above, in the terminal bus bar (150 or 150') provided in the present invention, the portion where the electrode leads are connected by welding or the like (which can be said to be the long axis of the bus bar) is metal / volume expansion resin + conductive substance + adhesive /. It has a three-layer structure of metal. Under normal conditions, an electric current can flow between the terminal bus bar and the electrode leads, but at high temperatures, the volume expansion resin expands in volume at the volume expansion resin + conductive substance + adhesive, and between the conductive substances. Open and resistance will increase. Therefore, the resistance between the terminal bus bar and the electrode lead becomes large, and the current flow becomes difficult. As described above, since the current does not flow through the terminal bus bar at the abnormal temperature, the safety of the battery module including the current does not flow, and the safety of the battery module including the current does not flow.

FIG. 4 schematically shows a battery module including a terminal busbar according to another embodiment of the present invention. FIG. 5 is a front view of the terminal bus bar portion included in the battery module of FIG. 4, and FIG. 6 is a cross-sectional view taken along the line VI-VI'of FIG. FIG. 7 is a front view of the bus bar portion included in the battery module of FIG.

The battery module 1000 of FIG. 4 shows a 4P3S connection example. That is, three cell banks 211 in which four battery cells 210 are connected in parallel (P) are connected in series (S). Each of the battery cells 210 can be a pouch-type battery cell as shown in FIG. 4P3S is merely an example and does not limit the battery module of the present invention.

The battery cell 210 is a secondary battery and includes two electrode leads 240 drawn out of the pouch case 230. The electrode lead 240 is divided into a positive electrode (+) lead and a negative electrode (−) lead according to the electrical polarity, and is electrically connected to an electrode assembly (not shown) sealed in the pouch case 230. That is, the positive electrode lead is electrically connected to the positive electrode plate of the electrode assembly, and the negative electrode lead is electrically connected to the negative electrode plate of the electrode assembly. As described above, the battery cell 210 has a structure in which an electrode assembly in which one end of an electrode lead 240 having opposite polarity is connected to both ends is housed in a pouch case 230 together with an electrolytic solution and sealed, and the other end of the electrode lead 240. This is a pouch-type secondary battery whose part is exposed to the outside of the pouch case 230.

Electrode leads 240 project from both ends of the battery cell 210. In the cell bank 211 connected in parallel, these electrode leads 240 are laminated so that they have the same polarity and are located in the same direction. Then, they are laminated so as to have opposite polarities between the cell banks 211. There are various connection methods for the electrode leads 240, but in FIGS. 4 to 7, the other end of the electrode leads 240 is bent to the left or right to provide a flat contact surface. A configuration is shown in which this is overlapped with the bus bar 290 or the terminal bus bar 150'and connected by welding.

Referring to FIGS. 4 to 7, the terminal bus bar 150'connects electrode leads 240 having the same polarity in one cell bank 211. The bus bar 290 connects electrode leads 240 having different polarities between the two cell banks 211. In this embodiment, two terminal bus bars 150'and two bus bars 290 are provided.

The terminal bus bar 150'and the bus bar 290 are arranged parallel to the stacking direction of the battery cells 210 and connected to the electrode leads 240 between the bent portions of the electrode leads 240. The connection method may be the usual method in the industry. For example, they can be joined and connected by ultrasonic welding, laser welding, but not limited to this.

The terminal bus bar 150'and the bus bar 290 are formed with through ports 168 and 296 through which the electrode leads 240 penetrate. For the terminal bus bar 150', the description with reference to FIGS. 2 and 3 is substituted.

Looking at FIG. 5 which is a front view of the terminal bus bar 150'and FIG. 7 which is a front view of the bus bar 290, the through holes 168 and 296 are substantially O-shaped. After the electrode lead 240 penetrates and is bent through the through hole 168 and 296 formed in the center, the welding between the electrode lead 240 and the bus bar 150'290 is linear along the long axis of the bus bar 150' and 290. Will be done.

In particular, as shown in FIGS. 4 and 5, four electrode leads 240 may be coupled to the second metal layer 166 of the coupling portion 160 of one terminal bus bar 150'. In this way, when four electrode leads 240 are coupled to the coupling portion 160 of one terminal bus bar 150', two of the four electrode leads 240 penetrate through the through port 168 in a state of being laminated with each other. Can be bent to the left and connected to the left side of the coupling 160, and the remaining two electrode leads 240 can be bent to the left and connected to the right side of the coupling 160.

At this time, the four electrode leads 240 are provided in the four different battery cells 210, and have the same polarity as each other. For example, the electrode leads 240 connected to the terminal bus bar 150'at the upper right end of FIG. 4 are all positive electrode leads. Therefore, the terminal bus bar 150'at the upper right end of FIG. 4 can be said to be a positive electrode terminal bus bar. The electrode leads 240 connected to the terminal bus bar 150'at the lower left end of FIG. 4 are all negative electrode leads. Therefore, the terminal bus bar 150'at the lower left end of FIG. 4 can be said to be a negative electrode terminal bus bar.

With reference to FIGS. 4 and 7, eight electrode leads 240 may be coupled to one bus bar 290. In this way, when eight electrode leads 240 are coupled to one bus bar 290, two of the eight electrode leads 240 are bent to the right in a state of being laminated with each other and connected to the left side of the bus bar 290. The other two, in a state of being stacked on each other, pass through the left through hole 296 of the two through holes 296, are bent to the right, and are connected to the left side of the central portion of the bus bar 290. Further, the other two are laminated to each other, pass through the right through hole 296 of the two through ports, are bent to the left side, and are connected to the right side of the central portion of the bus bar 290. The remaining two electrode leads 240 are bent to the left and connected to the right side of the bus bar 290.

At this time, the eight electrode leads 240 are provided in eight different battery cells 210, respectively, the four on the left side have the same polarity as each other, and the four on the right side are different from these. Has polarity. For example, the electrode leads 240 connected to the bus bar 290 are four positive electrode leads and four negative electrode leads.

In particular, the current flow path through the terminal bus bar 150'of the present invention will be described in detail with reference to FIG. Referring to FIG. 6, the current flow path from the outside of the battery module (1000 in FIG. 4) to the battery module 1000 is the terminal portion 170 of the terminal bus bar 150', the first metal layer 162, the material layer 164, and the first. The electrode leads 240 are provided in this order via the two metal layers 166. As described above, the material layer 164 is a material that is always conductive, but functions as a resistance when the temperature rises. When the temperature rises above a predetermined temperature due to an abnormal situation, for example, when the temperature rises above 300 ° C., melamine cyanurate is decomposed in the substance layer 164 to generate _N2 gas. As a result, the material layer 164 has increased resistance and functions as a resistance layer. It can also play a role in disconnecting electrical connections by volume expansion.

Therefore, under normal conditions, the conductivity of the material layer 164 in the terminal bus bar 150'is maintained and battery module performance similar to that of existing bus bars can be exhibited. When the temperature rises above a predetermined temperature due to an abnormal situation, the resistance of the material layer 164 increases, so that the current flowing to the terminal portion 170 and the first metal layer 162 flows to the second metal layer 166 via the material layer 164. It becomes difficult. Therefore, the flow of current to the electrode lead 240 can be cut off. As a result, when the temperature rises, the material layer 164 functions as a resistance and can cut off the current. Therefore, even if the secondary battery protection circuit does not operate, it is possible to cut off the current flow to prevent further current flow, for example, to prevent charging, and to improve the safety of the battery module 1000. Can be enhanced. As described above, the battery module 1000 of the present invention embodies a means for automatically shutting off the current flow when the temperature rises by improving the terminal bus bar. Therefore, the battery module 1000 has a dual battery with an overcharge prevention function of the secondary battery protection circuit. It also has the effect of ensuring the safety of the module 1000. By configuring the terminal bus bar 150'rather than the bus bar 290 in this way, the flow of current to the battery module 1000 is fundamentally cut off from the outside or from other battery modules.

A typical cause of a sudden rise in the temperature of a lithium secondary battery and a decrease in safety is the generation of a short-circuit current, which is short-circuited in terms of the safety of a battery module or battery pack in which multiple battery cells are connected. Ensuring time safety is very important. The lower the short-circuit resistance, the higher the short-circuit current will flow and a large amount of heat will be generated, and if the battery cell cannot withstand it, ignition will occur. Sometimes safe results are obtained when the short circuit resistance is very low, but this is because the heat generated while the high current is flowing exceeds 660 ° C and the electrode leads are melted, which cuts off the current flow. This is the case when safety is ensured. If the generated temperature is lower than this, the electrode leads will not melt, high heat will be accumulated while the current flow continues, the battery cell will not be able to withstand, and ignition will occur. On the other hand, a high current may flow even under normal conditions. During situations such as rapid charging, rapid acceleration, and starting in an electric vehicle, a large current will flow through the battery module, which will cause high temperatures in the electrode leads. Under such a normal situation, the current cutoff operation should not be performed. In order to prevent this, it is necessary to cut off the current flow at a temperature of about 250 ° C. or higher.

In this embodiment, when the battery module 1000 reaches about 300 ° C., gas is generated in the material layer 164 of the terminal bus bar 150'so that the resistance of the material layer 164 increases. As a result, it does not operate in the normal high current range, but operates only when a short circuit actually occurs and overheats to a temperature higher than that, so that safety against fire, explosion, etc. due to the short circuit can be ensured. Further, unlike other safety improving devices such as PTC elements and fuses, it does not occupy space in the module, so that it has an advantage that the energy density is not reduced.

Since the battery module 1000 according to the present invention has excellent safety, it is also suitable for use as a power source for medium- and large-sized devices that require high-temperature stability, long cycle characteristics, and high rate characteristics. Desirable examples of the medium- and large-sized devices are power tools that are powered by electric motors; electric vehicles including EVs, HEVs, PHEVs, etc .; electric bicycles (E-bikes), electric scooters (E). -Scooters, including, but not limited to, electric motorcycles; electric golf carts; and ESS.

The terminal bus bar 150'and the bus bar 290 can vary in form and size in order to embody various electrical connection relationships. Rather than using the terminal bus bar 150'and the bus bar 290 alone, they are applied to the battery module manufacturing process as parts such as an ICB assembly combined on a frame made of a plastic material in consideration of wiring. The form of the frame and the form of the bus bar combined with the frame vary depending on the connection relationship of the battery modules. Therefore, those skilled in the art will appreciate that various variations of the present invention are possible.

FIG. 8 shows a photograph of an experimentally manufactured ICB assembly.

The ICB assembly 300 includes a frame 310, a bus bar 290 and a terminal bus bar 150'.

Since the terminal bus bar 150'can be fixed to the frame 310 by piercing or the like, as presented in the present invention, the volume expansion resin + conductive substance is planarly formed between the first metal layer 162 and the second metal layer 166. Even if a substance layer 164 such as + adhesive is interposed, the volume expansion resin + conductive substance + adhesive and the first metal layer 162, the volume expansion resin + conductive substance + adhesive and the second metal layer There is no problem of slipping or separating from 166.

As described above, according to the present invention, the safety can be improved by improving the terminal bus bar of the battery module. By simply manufacturing the battery module 1000 using the terminal bus bar 150'according to the present invention instead of the existing bus bar, the stability is improved and the existing battery cell manufacturing process is used as it is, so that it can be used for process changes and mass production processes. On the other hand, there is no need for adjustment, which is also an advantage.

As described above, according to the present invention, under normal conditions, the conductivity of the material layer 164 in the terminal bus bar 150'is maintained, and while exhibiting battery module performance similar to that of existing battery modules, depending on abnormal conditions. When the temperature rises above a predetermined temperature, the current flow can be cut off to improve the safety of the battery module 1000. Therefore, the safety of the battery module 1000, the battery pack including the battery module 1000, and the vehicle including the battery pack can be improved.

FIG. 9 is a diagram for explaining a battery pack according to still another embodiment of the present invention.

The battery pack 1200 includes two or more battery modules 1000 as described above. The interbus bar 1250 connects the terminal portions 170 of the terminal bus bar 150'between the adjacent battery modules 1000. That is, the interbus bar 1250 connects the terminal portion 170 of the terminal bus bar 150'of any one of the two or more battery modules 1000 and the terminal portion 170 of the other terminal bus bar 150'of the battery module 1000. Then, the battery modules 1000 are connected to each other.

The interbus bar 1250 may have a plate shape adjacent to the terminal portion 170 of the terminal bus bar 150'. The position of the terminal busbar 150'in the battery module 1000 can be adjusted to simplify the shape of the interbus bar 1250, i.e., so that the adjacent terminal busbar 150'is located at the closest distance. For example, in the example of FIG. 9, the battery module 1000 of FIG. 4 is located at the lower end of FIG. 9, and the battery module 1000 formed of the battery module 1000 of FIG. 4 symmetrically is located at the upper end of FIG. Is.

In the structure as shown in FIG. 9, the terminal bus bar 150'located at the upper right end is a negative electrode terminal bus bar. The terminal portion 170 of the terminal bus bar 150'is provided with a negative electrode terminal that is electrically connected to an external terminal for external input. The two terminal bus bars 150'located in the middle portion on the left side are a positive electrode terminal bus bar and a negative electrode terminal bus bar in this order from the top to the bottom of the drawing. As a result, the interbus bar 1250 connects two terminal bus bars 150'of different polarities in series. The terminal bus bar 150'at the lower right end is a positive electrode terminal bus bar. The terminal portion 170 of the terminal bus bar 150'is provided with a positive electrode terminal that is electrically connected to an external terminal for external input.

The connection between the terminal bus bar 150'and the interbus bar 1250 may be a bolt-nut fastening method using a hole 172 formed in the terminal portion 170 of the terminal bus bar 150'. Therefore, the interbus bar 1250 may be provided with other holes for fastening bolts and nuts at positions corresponding to holes 172.

The battery pack 1200 may further include a pack case for packaging the battery module 1000. Further, the battery pack 1200 according to the present invention includes various devices for controlling charging / discharging of the battery module 1000, for example, a BMS (Battery Management System), a current sensor, and a fuse, in addition to the battery module 1000 and the pack case. Etc. may be further included.

FIG. 10 is a diagram for explaining an automobile according to still another embodiment of the present invention.

Such a battery pack 1200 can be provided in the vehicle 1300 as a fuel source for the vehicle 1300. For example, the battery pack 1200 may be included in electric vehicles, hybrid vehicles and other types of vehicles 1300 that can use the battery pack 1200 as a fuel source.

Desirably, the vehicle 1300 can be an electric vehicle. The battery pack 1200 can be used as an electrical energy source to drive the vehicle 1300 by providing driving force to the motor 1310 of the electric vehicle. In this case, the battery pack 1200 has a high nominal voltage of 100 V or higher. In the case of a hybrid vehicle, it is adjusted to 270V.

The battery pack 1200 can be charged or discharged by the inverter 1320 by driving the motor 1310 and / or the internal combustion engine. The battery pack 1200 can be charged by a regenerative charging device combined with a brake. The battery pack 1200 may be electrically connected to the motor 1310 of the vehicle 1300 via the inverter 1320.

As mentioned above, the battery pack 1200 also includes BMS. The BMS estimates the state of the battery cell in the battery pack 1200, and manages the battery pack 1200 by using the estimated state information. For example, the state information of the battery pack 1200 such as SOC (State Of Charge), SOH (State Of Health), maximum input / output power allowance, and output voltage of the battery pack 1200 is estimated and managed. Then, it is possible to control the charging or discharging of the battery pack 1200 by using such state information, and to estimate the replacement time of the battery pack 1200.

The ECU 1330 is an electronic control device that controls the state of the automobile 1300. For example, torque information is determined based on information such as accelerator, brake, and speed, and the output of the motor 1310 is controlled according to the torque information. Further, the ECU 1330 transmits a control signal to the inverter 1320 so that the battery pack 1200 is charged or discharged based on the state information such as SOC and SOH of the battery pack 1200 transmitted by the BMS. The inverter 1320 causes the battery pack 1200 to be charged or discharged based on the control signal of the ECU 1330. The motor 1310 uses the electric energy of the battery pack 1200 to drive the automobile 1300 based on the control information (for example, torque information) transmitted from the ECU 1330.

Such an automobile 1300 includes a battery pack 1200 according to the present invention, and the battery pack 1200 includes a battery module 1000 with improved safety as described above. Therefore, the stability of the battery pack 1200 is improved, and since such a battery pack 1200 is excellent in stability and can be used for a long period of time, the automobile 1300 including the battery pack 1200 is safe and easy to operate. ..

Further, the battery pack 1200 may be provided not only in the automobile 1300 but also in other devices, appliances and equipment such as ESS and BMS using a secondary battery.

As described above, the devices, appliances and equipment provided with the battery pack 1200, such as the battery pack 1200 and the automobile 1300 according to the present embodiment, include the battery module 1000 described above, and thus have all the advantages of the battery module 100 described above. It is possible to embody devices, appliances and equipment such as a battery pack 1200 and an automobile 1300 equipped with such a battery pack 1200.

A battery module as shown in FIG. 4 was manufactured on a laboratory scale, and the current cutoff effect of the terminal bus bar according to the present invention was verified.

The battery cells constituting the battery module were manufactured by a normal pouch-type battery cell manufacturing method. A bus bar containing a first metal layer laminated in order like the terminal bus bar 150'according to the present invention / a substance layer which is always conductive but functions as a resistance when the temperature rises / a second metal layer was used. That was the example. The material layer, which is always conductive but acts as a resistance when the temperature rises, contains a gas generating material, a conductive material and an adhesive. Melamine cyanurate was used as the gas generating material, silver (Ag) powder was used as the conductive substance, and epoxy resin was used as the adhesive. The silver content was about 75-85 wt%.

Comparative Example 1 was the use of a bus bar composed of only one metal layer. In Comparative Example 2, a bus bar in which the first metal layer and the second metal layer were adhered with a silver epoxy resin was used. The materials of the first metal layer and the second metal layer and the material of the bus bar of Comparative Example 1 were the same. The sizes of the bus bars of Examples and Comparative Examples 1 and 2 were all the same.

FIG. 11 is a graph showing the resistance and temperature of the battery module used in the experiment with time. The resistance and temperature change with time were measured while applying an overcurrent of 600 A to the battery module. A 1000A class charger / discharger was used to apply the overcurrent, and a data logger was used to measure the data. The temperature was measured at the bus bar part of the battery module.

Referring to FIG. 11, in Comparative Example 1, as time passed, the temperature increased almost linearly, and after 30 seconds, the temperature was close to 60 ° C., and the resistance gradually increased, but through the bus bar. It shows that the generated current continues to flow. In the case of Comparative Example 2, it can be confirmed that as time elapses, the temperature rises more rapidly than that of Comparative Example 1 and reaches 110 ° C. when 30 seconds have passed. It is confirmed that the resistance of Comparative Example 2 gradually increases while maintaining a slightly larger degree than that of Comparative Example 1, but the current continues to flow through the bus bar and there is no effect of interrupting the overcurrent.

Looking at the examples, it can be seen that the overcurrent was cut off and the resistance measurement became impossible because the resistance increased sharply when 8 seconds had passed and the resistance was measured as 0 thereafter. The busbar according to the present invention can be called a PTC busbar because it not only shows an increase or decrease in resistance due to an increase in temperature but also shows a temperature characteristic in which resistance rapidly increases at a specific temperature. As described above, according to the present invention, it was confirmed that the resistance of the bus bar rapidly increases at a specific time point to generate an overcurrent cutoff effect. 12a, 12b, 13a and 13b are the results of an external short circuit test of the battery module used in the experiment. 12a and 12b are the cases of Comparative Example 1, and FIGS. 13a and 13b are the cases of the examples of the present invention. The external short-circuit test was performed by connecting a shunt resistor whose resistance value is known to the battery module in parallel, and measuring the shunt voltage applied to the shunt resistor while short-circuiting by passing a large current to calculate the current. The cell voltage was also measured during the test, and the temperatures of the bus bar, positive electrode, negative electrode and cell center were also measured. The data was measured using a data logger in the same manner as described above.

12a and 13a are voltage, temperature, and current graphs over time, and FIGS. 12b and 13b show the shunt voltage and current by enlarging the portion at the time when the external short circuit occurs.

Both FIGS. 12a and 13a show the results of forcibly causing an external short circuit 10 minutes after the application of the current. With the passage of time, in the case of Comparative Example 1 of FIG. 12a, the cell voltage is recovered to 3.15V, but in the case of the embodiment of FIG. 13a, the cell voltage is recovered to 4.25V. In Comparative Example 1, the fact that about 1.1 V was not recovered suggests that the current was not completely cut off. Looking at FIG. 12b, which actually shows the shunt voltage and current at the time of the external short circuit, in the case of Comparative Example 1, it is confirmed that a current of 300 A or more flows after the external short circuit, while FIG. 13b shows. In the case of the embodiment, it is confirmed that the current is close to 0 after the external short circuit.

Comparing the temperatures of the busbars, in the case of the example of FIG. 13a as compared with the case of the case of Comparative Example 1 of 12a, as a result of the resistance increasing due to the initial rapid temperature rise, the current is cut off and almost no current flows. I understand. In the case of the example, since the current cutoff effect is certain, the temperature of the positive electrode and the negative electrode of Comparative Example 1 rises to around 100 ° C., whereas in the case of the example, the temperature after the current cutoff is maintained at almost normal temperature. Has been done.

From the above experimental results, it can be confirmed that the examples of the present application have a more reliable current cutoff effect than the comparative examples, and actually perform the current cutoff function when the temperature increases.

Although the present invention has been described above with reference to limited examples and drawings, the present invention is not limited to this, and the technical idea and claims of the present invention are made by a person having ordinary knowledge in the technical field to which the present invention belongs. Needless to say, various modifications and modifications are possible within the equal range of.

1 Battery module 10, 10'Battery cell 20 Electrode assembly 30 Pouch case 40, 40' Electrode lead 50 Bus bar 100 Battery module 150, 150'Bass bar 160 Bonding part 162 First metal layer 164 Material layer 166 Second metal layer 168 Penetration Port 170 Terminal 172 Hole 210 Battery Cell 211 Cell Bank 230 Pouch Case 240 Electrode Lead 290 Bus Bar 296 Through Port 300 ICB Assembly 310 Frame 1000 Battery Module 1200 Battery Pack 1250 Interbus Bar 1300 Automobile 1310 Motor 1320 Inverter

Claims (13)

With an almost plate-shaped joint that is thinner than the length and width,
Including a terminal portion bent in the vertical direction at one end of the joint portion.
The joint portion is formed from a first metal layer / always conductive, which is laminated in order along the extension direction of the terminal portion, but from a substance layer / a second metal layer that functions as a resistance when the temperature rises. Become
The material layer contains a gas generating material that increases resistance by decomposing above a predetermined temperature to generate gas.
A terminal bus bar, wherein the first metal layer is integrated with the terminal portion, and the second metal layer provides a connecting surface with an electrode lead of a battery cell. The terminal bus bar according to claim 1, wherein the substance layer contains the gas generating material, a conductive substance, and an adhesive. The terminal bus bar according to claim 1 or 2, wherein the gas generating material is melamine cyanurate. The second aspect of the present invention, wherein the conductive substances are connected and fixed to each other by the adhesive, and when the gas is generated, the connection of the conductive substances is released and the resistance is increased. Terminal bus bar. The method for manufacturing the terminal bus bar according to any one of claims 1 to 4.
At the stage of preparing a metal member whose first metal layer is integrated with the terminal portion and whose cross section is L-shaped,
On the first metal layer, a material layer that is always conductive but functions as a resistance when the temperature rises is formed.
A method for manufacturing a terminal bus bar, which comprises a step of laminating a second metal layer on the material layer. The substance layer is formed by containing the gas generating material, a conductive substance, and an adhesive, and further comprises a step of laminating the second metal layer on the substance layer and then pressing the substance layer. Item 5. The method for manufacturing a terminal bus bar according to Item 5. A battery module that contains two or more battery cells
The battery cell is a pouch-type secondary battery in which electrode leads having opposite polarities are exposed to the outside of the pouch case.
Further including a terminal busbar connected to the electrode leads of one or more of the battery cells.
The terminal bus bar has an almost plate-shaped joint that is thinner than the length and width.
Including a terminal portion bent in the vertical direction at one end of the joint portion.
From the first metal layer / always conductive, but when the temperature rises, the material layer / second metal layer that functions as a resistance when the joint portion is laminated in order along the extension direction of the terminal portion. Become
The material layer contains a gas generating material that increases resistance by decomposing above a predetermined temperature to generate gas.
A battery module, wherein the first metal layer is integrated with the terminal portion, and the second metal layer is connected to the electrode lead. The battery module according to claim 7, wherein the substance layer contains the gas generating material, a conductive substance, and an adhesive. The battery module according to claim 7 or 8, wherein the gas generating material is melamine cyanurate. The eighth aspect of the present invention, wherein the conductive substances are connected and fixed to each other by the adhesive, and when the gas is generated, the connection of the conductive substances is released and the resistance is increased. Battery module. The current flow path from the outside of the battery module to the battery module is provided in the order of the terminal portion, the first metal layer, the material layer, the second metal layer, and the electrode leads. The battery module according to any one of claims 7 to 10. Includes two or more battery modules according to any one of claims 7 to 11.
A battery further including an interbus bar that connects a terminal portion of a terminal bus bar of any one of the battery modules and a terminal portion of the other terminal bus bar of the battery modules to connect the battery modules to each other. pack. An automobile comprising at least one battery pack according to claim 12.

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